Re: Saturable Reactors as Ballast

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Original poster: FIFTYGUY@xxxxxxx 

Folks-

    Just like to add that my Miller "Dialarc" welder uses the 
Saturable Reactor principle. Instead of transformer taps or a system 
to mechanically move a core shunt, a pot on the front adjusts the 
control circuit. It has a schematic on the inside cover, but 
unfortunately, I can't get to it right now to copy it. But the Miller 
website has owner's manuals:

<http://www.millerwelds.com/service/ownersmanuals.php>http://www.millerwelds.com/service/ownersmanuals.php

I'm pretty sure this is the one for my welder:

<http://www.millerwelds.com/om/o314v_mil.pdf>http://www.millerwelds.com/om/o314v_mil.pdf

    The schematic shows only one DC control winding, but it may 
really be the two out-of-phase windings shown as one. Very simple 
arrangement, with the front control dial being a 15W rheostat 
directly controlling the DC control voltage. Nice to see everything 
first goes through an isolating transformer (with a separate winding 
to derive the input to the DC control's rectifier). The Magnetic 
Amplifier winding interconnections look a little complex, but there's 
also a high/low output switch thrown in there for welder output 
ranges. A full-wave bridge on the output for DC welding is obviously 
of no use to us (unless you were cascading Magnetic Amplifiers, and 
needed that kind of output for the control input to another Amplifier!).
    Another thing I thought of: keeping the DC control circuit's 
impedance high makes it easier to filter (if filtering is desirable?).

-Phil LaBudde